The present invention relates to caliper brake apparatus of the side-pull type for bicycles, and more particularly to center adjusting devices for such brake apparatus.
Brake apparatus of this type are widely used in bicycles. With caliper brake apparatus for bicycles, the shoes attached to the distal ends of opposed brake arms wear away varying amounts during years of use. Such wear takes place invariably unevenly. Especially in the case of side-pull type, uneven wear occurs very markedly, producing a difference in the shoe-to-rim clearance between the opposite sides of the wheel rim, with the result that the brake fails to operate properly on one side. This is likely to cause a serious accident.
Accordingly when a difference in the shoe-to-rim clearance occurs between opposite sides of the wheel, there arises the necessity of properly adjusting the clearance, but the adjustment requires a cumbersome procedure, needs much skill and is therefore difficult to make accurately.
Stated more specifically, conventional caliper brake apparatus comprise a pair of brake arms each carrying a brake shoe and turnably supported on a center bolt attached to the bicycle frame. A brake spring for biasing the opposed shoes away from each other is held by a retainer which is also attached to the bolt. For the adjustment of the brake apparatus, the center bolt is loosened from the frame first, and the distance between the rim and the shoes is properly adjusted by turning the brake arms and the center bolt about the axis of the bolt. The center bolt is thereafter tightened up.
The adjusting procedure is apparently cumbersome since it is necessary to loosen the brake apparatus from the frame first. The distance to which the shoes are adjusted relative to the rim is determined predominantly by empirical skill and is therefore inaccurate and is liable to alter when the bolt is tightened up again after the adjustment owing to the resulting torque.
Further even when the brake shoes have not been worn out unevenly, it is essential that the pair of the brake shoes be spaced at the same distance from the rim, whereas it is difficult to properly mount the brake apparatus on the frame by fastening for the same reason as stated above.